Method and apparatus for predicting favored supplemental channel transmission slots using transmission power measurements of a fundamental channel

ABSTRACT

A method and apparatus for selecting a favored transmission slot for communicating non-voice data in conjunction with a voice-data communication. The slot, reflecting a favored power level and transmission rate for transmitting the non-voice data on a supplemental channel, is selected based upon the transmission power levels for voice-data transmitted by a base station to a remote station on a fundamental channel. The favored transmission slot is selected without the remote station messaging information to the base station concerning frequency channel or interference information for the supplemental channel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wireless communications. Moreparticularly, the invention concerns a method and apparatus forpredicting power control requirements for a supplemental channel used inconjunction with a fundamental channel.

2. Description of the Related Art

Traditionally, wireless communication systems were required to support avariety of services. One such communication system is a code divisionmultiple access (CDMA) system which conforms to the “TIA/EIA/IS-95Mobile Station-Base Station Compatibility Standard for Dual-ModeWideband Spread Spectrum Cellular System,” hereinafter referred to asIS-95. The use of CDMA techniques in a multiple access communicationsystem is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREADSPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE ORTERRESTRIAL REPEATERS,” and U.S. Pat. No. 5,103,459, entitled “SYSTEMAND METHOD FOR GENERATING WAVEFORMS IN A CDMA CELLULAR TELEPHONESYSTEM,” both assigned to the assignee of the present invention, andco-pending U.S. patent application Ser. No. 09/382,438, entitled “METHODAND APPARATUS USING A MULTI-CARRIER FORWARD LINK IN A WIRELESSCOMMUNICATION SYSTEM,” each of which is incorporated by referenceherein.

More recently, wireless systems such as the CDMA systems mentioned abovehave offered hybrid services, such as providing both wireless voice anddata communications. To coordinate the implementation of such services,the International Telecommunications Union requested the submission ofproposed standards for providing high-rate data and high-quality speechservices over wireless communication channels.

In a CDMA system, a user communicates with the network through one ormore base stations. For example, a user on a remote station (RS) maycommunicate with a land-based data source, such as the Internet, bytransmitting data to a base station (BS) via a wireless link. This linkbetween the RS and the BS is commonly referred to as the “reverse link.”The BS receives the data and routes it through a base station controller(BSC) to the land-based data network. When data is transmitted from theBS to the RS, it is transmitted on the “forward link.” In CDMA IS-95systems, the forward link (FL) and the reverse link (RL) are allocatedto separate frequencies.

The remote station communicates with at least one base station during acommunication. However, CDMA RSs are also capable of communicating withmultiple BSs simultaneously, such as during soft handoff. Soft handoffis a process of establishing a new forward and reverse link with a newbase station before breaking the old links with the previous basestation. Soft handoff minimizes the probability of dropped calls, thatis, where a call is inadvertently disconnected from the system. A methodand apparatus for providing communications between an RS and more thanone BS during the soft handoff process is disclosed in U.S. Pat. No.5,267,261, entitled “MOBILE ASSISTED SOFT HANDOFF IN A CDMA CELLULARTELEPHONE SYSTEM,” assigned to the assignee of the present invention andincorporated by reference herein.

Given the growing demand for wireless data applications, the need forvery efficient voice and data wireless communication systems has becomeincreasingly significant. One method for transmitting data in codechannel frames of fixed size is described in detail in U.S. Pat. No.5,504,773, entitled “METHOD AND APPARATUS FOR THE FORMATTING OF DATA FORTRANSMISSION,” assigned to the assignee of the present invention andincorporated by reference herein. In accordance with the IS-95 standard,non-voice data or voice data is partitioned into code channel framesthat are 20 msec wide with data rates as high as 14.4 Kbps.

A significant difference between voice services and data services is thefact that voice services have stringent fixed delay requirements.Typically, the overall one-way delay of voice services must be less than100 msec. In contrast, selectively planned data service delays, evenabove 100 msec, can be used to optimize the efficiency of thecommunication system. For example, error correction coding techniquesthat require relatively long delays can be used with data servicetransmissions.

Some parameters that measure the quality and effectiveness of datatransmissions are the transmission delay required for transferring adata packet, and the average throughput rate of the system. As explainedabove, a transmission delay does not have the same impact in data or“non-voice” communication as it does for a voice or “voice-data”communication. Still, delays cannot be ignored because they are animportant metric for measuring the quality of the data communicationsystem. The average throughput rate is reflective of the efficiency ofthe data transmission capability of the communication system.

Further, in a wireless communication system, capacity is maximized whenthe transmission energy for a signal is kept to a minimum value whilesatisfying the quality performance requirements for the signal. That is,the quality of transmitted voice-data or non-voice data cannot besignificantly degraded when received. One measure of the quality of areceived signal is the carrier-to-interference ratio (C/I) at thereceiver. Thus, it is desirable to provide a transmission power controlsystem that maintains a constant C/I at a receiver. Such a system isdescribed in detail in U.S. Pat. No. 5,056,109, entitled “Method andApparatus for Controlling Transmission Power in a CDMA CellularTelephone System,” assigned to the assignee of the present invention andincorporated by reference herein.

It is well known that in cellular systems the C/I of any given user is afunction of the location of the RS within a coverage area. In order tomaintain a given level of service, TDMA and FDMA systems resort tofrequency reuse techniques, i.e. not all frequency channels and/or timeslots are used in each base station. In a CDMA system, the samefrequency channel allocation is reused in every cell of the system,thereby improving the overall efficiency. The C/I associated with an RSdetermines the information rate that can be supported on the forwardlink from the base station to the user's RS. An exemplary system fortransmitting high rate digital data in a wireless communication systemis disclosed in co-pending U.S. patent application Ser. No. 6,574,211,issued Jan. 3, 2003, entitled “METHOD AND APPARATUS FOR HIGHER RATEPACKET DATA TRANSMISSION,” assigned to the assignee of the presentapplication and incorporated by reference herein.

Because the C/I associated with a RS determines the information ratethat can be supported on the forward link, it is useful to knowtransmission information for each frequency channel used and historicC/I information. This information is commonly collected at the RS andmessaged to the BS. But this messaging uses valuable system resources.What is needed is an invention that would eliminate such messagingrequirements. Preferably, the BS transmission power levels on a firstchannel would be used to predict favorable slots for transmittingadditional data on a second channel.

SUMMARY OF THE INVENTION

Broadly, the present invention solves a new technical challenge posed bythe increasing demand for wireless communication services. The inventionconcerns a method and apparatus for selecting a favored transmission“slot” for non-voice data that is transmitted in conjunction with avoice-data communication. The slot, reflecting a desirable power leveland transmission rate for the non-voice data, is selected based upon thetransmission power levels for voice-data transmitted by a base stationto a remote station.

In one embodiment, the invention may be implemented to provide a methodfor predicting a favored slot for transmitting non-voice data on asupplemental channel used in a wireless communication system. Generally,metrics reflecting the quality of voice-data signals sent by a baselocation are measured at a remote station. One or more of the metrics,or a value representing the quality of the received signal, is messagedfrom the remote station to the base location. If desirable, the baselocation may adjust the voice-data transmission power in considerationof the messages or values. Concurrently, the forward link voice-datatransmission power levels are monitored at the base location. Thevoice-data is transmitted to the remote station using the first channel,more specifically referred to herein as a fundamental channel.

In one embodiment, a dynamic transmission power value is computed usingvarious voice-data transmission power levels transmitted on the firstchannel. This value is then used to select a desired slot fortransmitting additional data. This additional data is transmitted on asecond channel such as a supplemental channel, shared or not shared,using a desired transmission power level and data rate for transmittingthe additional data.

In another embodiment, the invention provides an article of manufacturecontaining digital information executable by a digital signal-processingdevice. In yet another embodiment, the invention yields an apparatusused to practice the methods of the invention. The apparatus maycomprise a remote station and at least one base station that has,amongst other things, a transceiver used to communicate informationsignals to the remote station. Obviously, to receive signals, the remotestation also includes a transceiver communicatively coupled to the basestation, and possibly satellites where applicable. The apparatus willalso include at least one digital data processing apparatus, such as amicroprocessor or application specific integrated circuit (ASIC), thatis communicatively coupled to the network or one of its component parts.

The invention provides its users with numerous advantages. One advantageis that it allows power control of a supplemental channel to beestablished based upon the base location transmitted power forvoice-data. Another advantage is that the invention reduces systemresource costs currently experienced by communication networks. Thesenetworks rely on messages received from a remote station regarding thequality of the supplemental channel signal as received at the remotestation. Yet another advantage is that the invention allows a favorabletransmission slot in any channel carrying non-voice data to be selectedusing historic base location transmission power levels for voice data.The invention also provides a number of other advantages and benefitsthat should become even more apparent after reviewing the followingdetailed descriptions of the invention.

BRIEF DESCRIPTION OF THE DRAWING

The nature, objects, and advantages of the invention will become moreapparent to those skilled in the art after considering the followingdetailed description in connection with the accompanying drawings, inwhich like reference numerals designate like parts throughout, andwherein:

FIG. 1 illustrates transmission power fluctuations with respect to timein accordance with the invention;

FIG. 2 illustrates favorable supplemental channel transmission powers inaccordance with one embodiment of the present invention;

FIG. 3 shows a flow chart illustrating an operating sequence inaccordance with one embodiment of the present invention;

FIG. 4a is a block diagram of a general configuration for a mobilestation used in accordance with the invention;

FIG. 4b is a block diagram of a general channel structure used inaccordance with the invention;

FIG. 5a is a block diagram of the hardware components andinterconnections of a digital signal processing apparatus used inaccordance with the invention;

FIG. 5b is a block diagram of the hardware components andinterconnections of the modulator 526 shown in FIG. 5a and used inaccordance with the invention;

FIG. 6a is a block diagram of a portion of the hardware components andinterconnections of a digital signal processing base station apparatusused in accordance with the invention;

FIG. 6b is a block diagram of the hardware components andinterconnections of the demodulator 604 shown in FIG. 6a and used inaccordance with the invention; and

FIG. 7 is an exemplary embodiment of a digital data storage medium inaccordance with the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1-7 illustrate examples of the various method and apparatusaspects of the present invention. For ease of explanation, but withoutany limitation intended, the apparatus examples are described in thecontext of a signal processing apparatus that may be embodied by varioushardware components and interconnections. Further arrangements for thesesignal processing apparatuses will become apparent to anyone skilled inthe art after reading the descriptions that follow.

OPERATION

IS-95 supports medium data rate (MDR) transmission of data by allowing abase location (BS) to communicate with a remote station (RS) using up toeight (8) forward links and up to eight (8) reverse links. Furtheradvances have been made allowing for even higher data rate (HDR)transmissions using somewhat similar systems. Generally, data can bemore efficiently communicated between a BS and a RS if it is transmittedat the lowest possible power level required for maintaining the qualityof the communication.

Transmission of voice-data generally relies on the large number ofuncorrelated users communicating with a base station and well-behavedMarkov voice statistics to balance both RF capacity and RF stability.These large numbers of uncorrelated users result in a forward link RFtransmit power distribution that is predictably stationary andlog-normal. Without this forward link RF power predictability, forwardlink power control and mobile assisted handoff would be unstable.

However, transmission of non-voice data, such as downloading data fromthe Internet, is not as well behaved. Data traffic often comes inbursts, resulting in relatively long periods of maximum ratetransmission followed by relatively long periods of minimum ratetransmission. With the advent of MDR and HDR networks, these effectsbecome even more pronounced. Unlike correlated voice links, these linksswitch between maximum rate and minimum rate together and power controltogether. This can cause the forward link power distribution as a wholeto be decidedly non-stationary and non-log-normal.

In a typical communication network, RS users have different radiofrequency (RF) requirements depending upon their location relative tothe base station or stations with which they are in communication. Theworse a user's RF environment, the more power a base station requires todeliver a fixed amount of data. Therefore, users experiencing a poor RFenvironment use more network capacity. For example, users in differentphysical locations will experience different fading conditions, such asa user passing into the RF shadow of a building, whereas another usermay be passing into the RF shadow of a tree. These conditions willreduce the strength of the received signals, resulting in a poorerquality received signal than if the fade had not occurred. To overcomefading, transmission power may be increased.

As shown in FIG. 1, the transmission power level for voice-datatransmitted from a BS to a RS may vary with time. For example, at time102 the power level used to transmit voice-data to a user #1 from a BSis at a maximum. At time 104, the power level required to transmitvoice-data to a user #2 is at a minimum. At time 106, the averagevoice-data transmission power level for users #1 and #2 is at a minimum.In one embodiment of the invention, the slot 108 shown in FIG. 2 is afavorable time, or slot, to transmit additional data on the data channelof user #2. This determination is made using the voice-data transmissionpower levels as measured at the base location. Selecting non-voice datato be transmitted to a user on a second channel based on predicted BSpower levels for voice-data transmissions on a first channel maximizesoverall data throughput and does not require any quality metricmessaging from the RS to the BS regarding the second channel.

This basic method assures that voice-data transmissions areguaranteed: 1) a minimum bandwidth; 2) a maximum delay window; and, 3) agiven data rate. However, non-voice data users generally have lessstringent communication quality requirements so the transmission datarate can be varied. However, the invention can also be used for solelynon-voice data transmissions. In this embodiment, non-voice data iscommunicated using one or more forward link channels, but having anoverall fixed total transmission power. The communication transmits atdata rates that ensure the transmission power level is below the totalallowable transmission power level. This is accomplished first by usinga full-rate fundamental channel and then adding supplemental channelsfor transmitting. The transmission power used to transmit on thesupplemental channels is determined from the transmission power measuredat the BS for transmissions on the fundamental channel. Regardless, thetransmission power levels for the channels used to transmit thenon-voice data aggregate to a value below the total allowabletransmission power.

FIG. 3 is a flow chart reflecting method steps 300 for one embodiment ofthe present invention as used in a CDMA network. The method starts atstep 302 and data signals are transmitted in task 304 from a BS to a RS.As discussed above, this transmitted data may comprise voice and/ornon-voice data transmitted on a first channel, also referred to hereinas a fundamental channel. A first channel is a portion of the ForwardLink Channel that carries a combination of higher-level data and powercontrol information from the BS to the RS. A second channel is a portionof the Forward Link Channel that operates in conjunction with the firstchannel or a forward dedicated control channel to provide increased datadelivery services. A second channel is commonly referred to as asupplemental channel, but could be a dedicated fundamental channel.

As voice-data transmissions occur, the RS receiving the transmissionmeasures pre-selected metrics reflective of the quality of thecommunication received. These metrics can include bit error rate as wellas other commonly used metrics. If the quality of the received signalfalls off and remains poor, the RS messages a representative value tothe BS in task 308. This message may indicate that an increase,decrease, or no change in transmission power for data transmitted on thefirst channel is required. If necessary, the transmission power levelmay be adjusted in task 310.

As the BS transmits data on the fundamental channel, the transmissionpower levels are monitored at the BS in task 312. A dynamic valuereflecting the aggregated transmission levels and distributions isdetermined in task 314. In this embodiment, the dynamic value mayreflect the momentary average transmission power level. In otherembodiments, the dynamic value may be determined in a multitude of waysknown in the art, so long as the dynamic value represents the lowesttransmission power value at a selected point in time for first channeltransmissions. Using these dynamic values, the most favored slot fortransmission of data on a second channel may be predicted in task 316.Non-voice data for a RS user in need of the data may be selected and thedata transmitted. If the non-voice data communication is complete, thenthe method ends in task 320. However, if the communication is notcomplete, or if transmissions intended for another user are desired,then the method repeats itself in task 318.

HARDWARE COMPONENTS AND INTERCONNECTIONS

In addition to the various method embodiments described above, adifferent aspect of the invention concerns apparatus embodiments used toperform the methods.

FIG. 4a shows a simple block representation of a mobile station (MS) 401configured for use in accordance with the present invention. MS 401receives a signal from a base station (not shown) using a cdma2000multi-carrier FL. The signal is processed as described below. MS 401uses a cdma2000 RL to transmit information to the base station. FIG. 4bshows a more detailed block representation of a channel structure usedto prepare information for transmission by MS 401 in accordance with thepresent invention. In the figure, information to be transmitted,hereafter referred to as a signal, is transmitted in bits organized intoblocks of bits. A CRC & tail bit generator (GEN) 403 receives thesignal. The generator 403 uses a cyclic, redundancy code to generateparity check bits to assist in determining the quality of the signalwhen received by a receiver. These bits are included in the signal. Atail bit—a fixed sequence of bits—may also be added to the end of ablock of data to reset an encoder 405 to a known state.

The encoder 405 receives the signal and builds a redundancy into thesignal for error-correcting purposes. Different “codes” may be used todetermine how the redundancy will be built into the signal. Theseencoded bits are called symbols. The repetition generator 407 repeatsthe symbols it receives a predetermined number of times, thus allowingpart of the symbols to be lost due to a transmission error withoutaffecting the overall quality of the information being sent. Blockinterleaver 409 takes the symbols and jumbles them. The long codegenerator 411 receives the jumbled symbols and scrambles them using apseudorandom noise sequence generated at a predetermined chip rate. Eachsymbol is XOR-ed with one of the pseudorandom chips of the scramblingsequence.

The information may be transmitted using more than one carrier (channel)as explained with regards to the method, above. Accordingly, ademultiplexer (not shown) may take an input signal “a” and split it intomultiple output signals in such a way that the input signal may berecovered. In one embodiment the signal “a” is split into three separatesignals, each signal representing a selected data-type, and istransmitted using one FL channel per data-type signal. In anotherembodiment, the demultiplexer may split signal “a” into two componentsper data-type. Regardless of the arrangement, the present inventioncontemplates that distinct signals generated from a parent signal can betransmitted using one or more channels.

Further, this technique can be applied to multiple users whose signalsare transmitted using completely or partially the same FL channels. Forexample, if the signals from four different users are going to be sentusing the same three FL channels, then each of these signals is“channelized” by demultiplexing each signal into three components, whereeach component will be sent using a different FL channel. For eachchannel, the respective signals are multiplexed together to form onesignal per FL channel. Then, using the technique described herein, thesignals are transmitted. The demultiplexed signal is then encoded by aWalsh encoder (not shown) and spread into two components, components Iand Q, by a multiplier. These components are summed by a summer andcommunicated to a remote station (also not shown).

FIG. 5a illustrates a functional block diagram of an exemplaryembodiment of the transmission system of the present invention embodiedin a wireless communication device 500. One skilled in the art willunderstand that certain functional blocks shown in the figure may not bepresent in other embodiments of the invention. The block diagram of FIG.5b corresponds to an embodiment consistent for operation according tothe TIA/EIA Standard IS-95C, also referred to as IS-2000, or cdma2000for CDMA applications. Other embodiments of the present invention areuseful for other standards including the Wideband CDMA (WCDMA) standardsproposed by the standards bodies ETSI and ARIB. It will be understood byone skilled in the art that owing to the extensive similarity betweenthe reverse link modulation in the WCDMA standards and the reverse linkmodulation in the IS-95C standard, extension of the present invention tothe WCDMA standards may be accomplished.

In the exemplary embodiment of FIG. 5a, the wireless communicationdevice transmits a plurality of distinct channels of information whichare distinguished from one another by short orthogonal spreadingsequences as described in the U.S. Pat. No. 6,396,804 entitled “HIGHDATA RATE CDMA WIRELESS COMMUNICATION SYSTEM,” by Joseph P. Odenwalder.assigned to the assignee of the present invention and incorporated by toreference herein. Five separate code channels are transmitted by thewireless communication device: 1) a first supplemental data channel 532,2) a time multiplexed channel of pilot and power control symbols 534, 3)a dedicated control channel 536, 4) a second supplemental data channel538 and 5) a fundamental channel 540. The first supplemental datachannel 532 and second supplemental data channel 538 carry digital datawhich exceeds the capacity of the fundamental channel 540 such asfacsimile, multimedia applications, video, electronic mail messages orother forms of digital data. The multiplexed channel of pilot and powercontrol symbols 534 carries pilots symbols to allow for coherentdemodulation of the data channels by the base station and power controlbits to control the energy of transmissions of the base station or basestations in communication with wireless communication device 500.Control channel 536 carries control information to the base station suchas modes of operation of wireless communication device 500, capabilitiesof wireless communication device 500 and other necessary signalinginformation. Fundamental channel 540 is the channel used to carryprimary information from the wireless communication device to the basestation. In the case of speech transmissions, the fundamental channel540 carries the speech data.

Supplemental data channels 532 and 538 are encoded and processed fortransmission by means not shown and provided to modulator 526. Powercontrol bits are provided to repetition generator 522, which providesrepetition of the power control bits before providing the bits tomultiplexer (MUX) 524. In MUX 524 the redundant power control bits aretime multiplexed with pilot FDIG symbols and provided on line 534 tomodulator 526.

Message generator 512 generates necessary control information messagesand provides the control message to CRC and tail bit generator 504. CRCand tail bit generator 504 appends a set of cyclic redundancy check bitswhich are parity bits used to check the accuracy of the decoding at thebase station and appends a predetermined set of tail bits to the controlmessage to clear the memory of the decoder at the base station receiversubsystem. The message is then provided to encoder 516, which providesforward error correction coding upon the control message. The encodedsymbols are provided to repetition generator 518, which repeats theencoded symbols to provide additional time diversity in thetransmission. The symbols are then provided to interleaver 520 thatreorders the symbols in accordance with a predetermined interleavingformat. The interleaved symbols are provided on line 536 to modulator526.

Variable rate data source 502 generates variable rate data. In theexemplary embodiment, variable rate data source 502 is a variable ratespeech encoder such as described in U.S. Pat. No. 5,414,796, entitled“VARIABLE RATE VOCODER,” assigned to the assignee of the presentinvention and incorporated by reference herein. Variable rate vocodersare popular in wireless communications because their use increases thebattery life of wireless communication devices and increases systemcapacity with minimal impact on perceived speech quality. TheTelecommunications Industry Association has codified the most popularvariable rate speech encoders in such standards as Interim StandardIS-96 and Interim Standard IS-733. These variable rate speech encodersencode the speech signal at four possible rates referred to as fullrate, half rate, quarter rate or eighth rate according to the level ofvoice activity. The rate indicates the number of bits used to encode aframe of speech and varies on a frame by frame basis. Full rate uses apredetermined maximum number of bits to encode the frame, half rate useshalf the predetermined maximum number of bits to encode the frame,quarter rate uses one quarter the predetermined maximum number of bitsto encode the frame and eighth rate uses one eighth the predeterminedmaximum number of bits to encode the frame.

Variable rate date source 502 provides the encoded speech frame to CRCand tail bit generator 504. CRC and tail bit generator 504 appends a setof cyclic redundancy check bits which are parity bits used to check theaccuracy of the decoding at the base station and appends a predeterminedset of tail bits to the control message in order to clear the memory ofthe decoder at the base station. The frame is then provided to encoder506, which provides forward error correction coding on the speech frame.The encoded symbols are provided to repetition generator 508, whichprovides repetition of the encoded symbol. The symbols are then providedto interleaver 510 and reordered in accordance with a predeterminedinterleaving format. The interleaved symbols are provided on line 540 tomodulator 526.

In the exemplary embodiment, modulator 526 modulates the data channelsin accordance with a code division multiple access modulation format andprovides the modulated information to a transmitter, which amplifies andfilters the signal and provides the signal through duplexer 528 fortransmission through an antenna. In IS-95 and cdma2000 systems, a 20 msframe is divided into sixteen sets of equal numbers of symbols, referredto as power control groups. The reference to power control is based onthe fact that for each power control group, the base station receivingthe frame issues a power control command in response to a determinationof the sufficiency of the received reverse link signal at the basestation.

FIG. 5b illustrates a functional block diagram of an exemplaryembodiment of modulator 526 of FIG. 5a. The first supplemental datachannel data is provided on line 532 to spreading element 542 whichcovers the supplemental channel data in accordance with a predeterminedspreading sequence. In the exemplary embodiment, spreading element 542spreads the supplemental channel data with a short Walsh sequence(++−−). The spread data is provided to relative gain element 544, whichadjusts the gain of the spread supplemental channel data relative to theenergy of the pilot and power control symbols. The gain adjustedsupplemental channel data is provided to a first summing input ofsumming element 546. The pilot and power control multiplexed symbols areprovided on line 534 to a second summing input of summing element 546.

Control channel data is provided on line 536 to spreading element 548which covers the supplemental channel data in accordance with apredetermined spreading sequence. In the exemplary embodiment, spreadingelement 548 spreads the supplemental channel data with a short Walshsequence (++++++++−−−−−−−−). The spread data is provided to relativegain element 550, which adjusts the gain of the spread control channeldata relative to the energy of the pilot and power control symbols. Thegain adjusted control data is provided to a third summing input ofsumming element 546. Summing element 546 sums the gain adjusted controldata symbols, the gain adjusted supplemental channel symbols and thetime multiplexed pilot and power control symbols and provides the sum toa first input of multiplier 562 and a first input of multiplier 568.

The second supplemental channel is provided on line 538 to spreadingelement 552 which covers the supplemental channel data in accordancewith a predetermined spreading sequence. In the exemplary embodiment,spreading element 552 spreads the supplemental channel data with a shortWalsh sequence (++−−). The spread data is provided to relative gainelement 554, which adjusts the gain of the spread supplemental channeldata. The gain adjusted supplemental channel data is provided to a firstsumming input of summer 556.

The fundamental channel data is provided on line 540 to spreadingelement 558 which covers the fundamental channel data in accordance witha predetermined spreading sequence. In the exemplary embodiment,spreading element 558 spreads the fundamental channel data with a shortWalsh sequence (++++−−−−++++−−−−). The spread data is provided torelative gain element 560 that adjusts the gain of the spreadfundamental channel data. The gain adjusted fundamental channel data isprovided to a second summing input of summing element 556. Summingelement 556 sums the gain adjusted second supplemental channel datasymbols and the fundamental channel data symbols and provides the sum toa first input of multiplier 564 and a first input of multiplier 566.

In the exemplary embodiment, a pseudonoise spreading using two differentshort PN sequences (PN_(I) and PN_(Q)) is used to spread the data. Inthe exemplary embodiment the short PN sequences, PN_(I) and PN_(Q), aremultiplied by a long PN code to provide additional privacy. Thegeneration of pseudonoise sequences is well known in the art and isdescribed in detail in U.S. Pat. No. 5,103,459, entitled “SYSTEM ANDMETHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONESYSTEM,” assigned to the assignee of the present invention andincorporated by reference herein. A long PN sequence is provided to afirst input of multipliers 570 and 572. The short PN sequence PN_(I) isprovided to a second input of multiplier 570 and the short PN sequencePN_(Q) is provided to a second input of multiplier 572.

The resulting PN sequence from multiplier 570 is provided to respectivesecond inputs of multipliers 562 and 564. The resulting PN sequence frommultiplier 572 is provided to respective second inputs of multipliers566 and 568. The product sequence from multiplier 562 is provided to thesumming input of subtractor 574. The product sequence from multiplier564 is provided to a first summing input of summing element 576. Theproduct sequence from multiplier 566 is provided to the subtractinginput of subtractor 574. The product sequence from multiplier 568 isprovided to a second summing input of summing element 576.

The difference sequence from subtractor 574 is provided to basebandfilter 578. Baseband filter 578 performs necessary filtering on thedifference sequence and provides the filtered sequence to gain element582. Gain element 582 adjusts the gain of the signal and provides thegain-adjusted signal to upconverter 586. Upconverter 586 upconverts thegain adjusted signal in accordance with a QPSK modulation format andprovides the unconverted signal to a first input of summing element 590.

The sum sequence from summing element 576 is provided to baseband filter580. Baseband filter 580 performs necessary filtering on differencesequence and provides the filtered sequence to gain element 584. Gainelement 584 adjusts the gain of the signal and provides thegain-adjusted signal to upconverter 588. Upconverter 588 upconverts thegain adjusted signal in accordance with a QPSK modulation format andprovides the upconverted signal to a second input of summing element590. Summing element 590 sums the two QPSK modulated signals andprovides the result to a transmitter (not shown).

Turning now to FIG. 6a, a functional block diagram of selected portionsof a base station 600 is shown in accordance with the present invention.Reverse link RF signals from the wireless communication device 500 (FIG.5b) are received by receiver (RCVR) 602, which downconverts the receivedreverse link RF signals to an baseband frequency. In the exemplaryembodiment, receiver 602 down converts the received signal in accordancewith a QPSK demodulation format. Demodulator 604 then demodulates thebaseband signal. Demodulator 604 is further described with reference toFIG. 6b below.

The demodulated signal is provided to accumulator 606. Accumulator 606sums the symbol energies of the redundantly transmitted power controlgroups of symbols. The accumulated symbol's energies are provided tode-interleaver 608 and reordered in accordance with a predeterminedde-interleaving format. The reordered symbols are provided to decoder610 and decoded to provide an estimate of the transmitted frame. Theestimate of the transmitted frame is then provided to CRC check 613which determines the accuracy of the frame estimate based on the CRCbits included in the transmitted frame.

In the exemplary embodiment, base station 600 performs a blind decodingon the reverse link signal. Blind decoding describes a method ofdecoding variable rate data in which the receiver does not know a priorithe rate of the transmission. In the exemplary embodiment, base station600 accumulates, deinterleaves and decodes the data in accordance witheach possible rate hypothesis. The frame selected as the best estimateis based on quality metrics such as the symbol error rate, the CRC checkand the Yamamoto metric.

An estimate of the frame for each rate hypothesis is provided to controlprocessor 617 and a set of quality metrics for each of the decodedestimates is also provided. Quality metrics that may include the symbolerror rate, the Yamamoto metric and the CRC check. Control processorselectively provides one of the decoded frames to the remote stationuser or declares a frame erasure.

In the preferred embodiment, demodulator 603 shown in FIG. 6a has onedemodulation chain for each information channel. An exemplarydemodulator 603 performs complex demodulation on signals modulated by anexemplary modulator. As previously described, receiver (RCVR) 602downconverts the received reverse link RF signals to a basebandfrequency, producing Q and I baseband signals. Despreaders 614 and 616respectively despread the I and Q baseband signals using the long codefrom FIG. 5a. Baseband filters (BBF) 618 and 620 respectively filter theI and Q baseband signals.

Despreaders 622 and 624 respectively despread the I and Q signals usingthe PN, sequence of FIG. 5b. Similarly, despreaders 626 and 628respectively despread the Q and I signals using the PN_(Q) sequence ofFIG. 5b. The outputs of despreaders 622 and 624 are combined in combiner630. The output of despreader 628 is subtracted from the output ofdespreader 624 in combiner 632. The respective outputs of combiners 630and 632 are then Walsh-uncovered in Walsh-uncoverers 634 and 636 withthe Walsh code that was used to cover the particular channel of interestin FIG. 5b. The respective outputs of the Walsh-uncoverers 634 and 636are then summed over one Walsh symbol by accumulators 642 and 644.

The respective outputs of combiners 630 and 632 are also summed over oneWalsh symbol by accumulators 638 and 640. The respective outputs ofaccumulators 638 and 640 are then applied to pilot filters 646 and 648.Pilot filters 646 and 648 generate an estimation of the channelconditions by determining the estimated gain and phase of the pilotsignal data 534 (see FIG. 5a). The output of pilot filter 646 is thencomplex multiplied by the respective outputs of accumulators 642 and 644in complex multipliers 650 and 652. Similarly, the output of pilotfilter 648 is complex multiplied by the respective outputs ofaccumulators 642 and 644 in complex multipliers 654 and 656. The outputof complex multiplier 654 is then summed with the output of complexmultiplier 650 in combiner 658. The output of complex multiplier 656 issubtracted from the output of complex multiplier 652 in combiner 660.Finally, the outputs of combiners 658 and 660 are combined in combiner662 to produce the demodulated signal of interest.

Despite the specific foregoing descriptions, ordinarily skilled artisanshaving the benefit of this disclosure will recognize that the apparatusdiscussed above may be implemented in a machine of differentconstruction without departing from the scope of the present invention.Similarly, parallel methods may be developed. As a specific apparatusexample, one of the components such as summing element 622, shown inFIG. 6b, may be combined with summing element 626 even though they areshown as separate elements in the functional diagram.

Signal-Bearing Media

The methods described above may be implemented, for example, byoperating a base station to execute a sequence of machine-readableinstructions. These instructions may reside in various types of signalbearing media such as illustrated in FIG. 7. In this respect, oneembodiment of the invention concerns a programmed product, or article ofmanufacture, comprising signal-bearing media tangibly embodying aprogram of machine-readable instructions executable by a digital signalprocessor to perform the methods discussed above.

The signal bearing media may comprise any type of digital data storagemedia. For example, this storage media includes an application specificintegrated circuit (ASIC), a digital data or optical storage deviceaccessible by the base station, electronic read-only memory, or othersuitable signal bearing media. In an illustrative embodiment of theinvention, the machine-readable instructions may comprise softwareobject code, compiled from a language such as C, C+, C++; or othercoding language.

OTHER EMBODIMENTS

While there have been shown what are presently considered to beexemplary embodiments of the invention, it will be apparent to thoseskilled in the art that various changes and modifications can be madewithout departing from the scope of the invention as defined by theappended claims.

What is claimed is:
 1. A method for predicting a favored slot fortransmitting data in a wireless communication system, the methodcomprising the steps of: transmitting signals between a base locationand a remote station via at least one first channel, wherein thetransmitted signals comprise voice-data; measuring at the base locationtransmission power levels for the voice-data transmitted via the atleast one first channel; determining a dynamic transmission power levelfor at least one first channel; and using the dynamic transmission powerlevel to select a second channel transmission slot and data rate fortransmitting additional data on a second channel.
 2. The method inaccordance with claim 1, further comprising the steps of: measuring atthe remote location transmission metrics reflecting the quality ofvoice-data signals received from the base location; messaging from theremote location to the base location any change or non-change in thevoice-data quality; and adjusting or not adjusting transmission power inconsideration of voice-data transmitted by the base location.
 3. Asignal bearing medium tangibly embodying a program of machine-readableinstructions executable by a digital signal processing apparatus toperform a method for predicting a favored slot for transmitting data ina wireless communication system, the instructions comprising the methodsteps of: transmitting signals containing voice-data between a baselocation and a remote location; measuring at the base locationtransmission power levels for voice-data transmitted via at least onefirst channel; determining a historical profile for the transmissionpower levels; and using the historical profile of the transmission powerlevels to select a second channel transmission power level and data ratefor transmitting additional data on a second channel.
 4. A signalbearing medium tangibly embodying a program of machine-readableinstructions executable by a digital signal processing apparatus toperform a method for predicting a favored slot for transmitting data ina wireless communication system, the instructions comprising the methodsteps of: transmitting signals containing voice-data between a baselocation and a remote location; measuring at the base locationtransmission power levels for voice-data transmitted via at least onefirst channel; determining a dynamic transmission power level; and usingthe dynamic transmission power level to select a second channeltransmission slot and data rate for transmitting additional data on asecond channel.
 5. An apparatus used to predict a favored slot fortransmitting data between a base location and a remote station in awireless communication system, the apparatus comprising: a base locationcommunicatively coupled to a remote station, wherein the base locationmay communicate with the remote station using more than one channel, thebase location comprising: a transmitter, the transmitter capable oftransmitting voice and non-voice data signals between a base locationand a remote station; and a digital signal processing apparatuscommunicatively coupled to the transmitter and capable of executinginstructions to: measure at the base location transmission power levelsfor voice-data transmitted to the remote station via at least one firstchannel; determining an dynamic transmission power level fortransmissions made via the at least one first channel; and using thedynamic transmission power level to select a second channel transmissionslot for transmitting additional data to the remote station on a secondchannel.
 6. The apparatus in accordance with claim 5, furthercomprising; a measuring means for measuring at the remote stationtransmission metrics reflecting the quality of voice-data signalsreceived from the base location; a messaging means for messaging to thebase location a value indicting any change or non-change in thevoice-data quality; and a means for adjusting or not adjusting thetransmission power in consideration of voice-data quality.